The present invention relates to a method for coating a substrate, such as a glass pane, to achieve an opaque effect.
Specifically, the invention provides a method for manufacturing a layer that has an opaque effect on a substrate, such as a glass pane, whereby the substrate is provided with a layer system, or with a layer, that has prescribed reflective properties to solar radiation and prescribed transmission properties in the visible solar range, i.e., a solar control coating.
The present invention also relates to an opaque coated substrate, such as a glass pane, having both a solar control coating and a layer of an opacifier, or opacifying layer.
A method for manufacturing substrates, wherein transparent substrates are coated with a solar control coating via cathode sputtering, is disclosed in German Published Application 3,311,815. Substrates manufactured by this method have a transmissibility of 10 to 40%, although preferably 15 to 30%, and further have a reflectivity capable of reflecting incident solar radiation.
The published application proposes that an oxide layer, having an optical thickness ranging from 20 to 280 nm, be sputtered directly onto a substrate in an oxygenated atmosphere. A second layer of chromium-nitride, having a geometrical thickness ranging from 10 to 30 nm, is sputtered onto the substrate in an atmosphere composed of inert gas and nitrogen. The above-identified patent application describes one of the many examples of solar control coatings.
Such solar control coatings are useful, for example, in the coating of architectural glass for building construction. As the needs for reflectivity and transmissibility of transparent substrates vary with climatic conditions, it is desirable to have a defined reflectivity and transmissibility when applying solar control coatings to materials, such as architectural glass.
For instance, depending on the intensity of the solar radiation, the solar control coating can have a heat insulating affect on transparent surfaces, such as architectural glass on a building. This heat insulating capability is intended to keep the interior of the building cool The transmission properties of the solar control coating can be adapted to different climates, or to different intensities of solar radiation. For instance, there are many known solar control coatings which have a number of individual layers that form a layer system. Each layer system can have a prescribed transmissibility. Thus, where solar intensity is greater, a lower transmissibility is required to insulate a structure, such as a building.
For example, in a building wall composed of architectural glass, such as an office skyscraper having numerous windows, it is desirable to achieve an overall visually uniform effect, even though the glass covers both window and non-window regions, the non-window regions can include masonry regions or cement walls. It is difficult to find a uniform glazing that can be used to coat the architectural glass in both the window and non-window regions, such that an observer on the exterior of the building cannot readily differentiate between the window and non-window regions of the architectural glass.
The reflectivity of the non-window regions should be comparable to that of the window regions. The transmissibility, however, must be extremely low in the non-window regions, such that an observer cannot see the masonry or cement behind the glass, as compared to the windows regions, where the transmissibility can be much greater.
In order to achieve an overall visually uniform effect across the surface of a transparent substrate, such as a building wall, gluing a foil or spraying a paint onto the glazing has been proposed.
These and other known coating methods are involved and expensive, and do not meet modern needs for achieving an overall visually uniform effect of a surface treated with a solar control coating.